Ternary escort memory system

ABSTRACT

In an addressing system of a transportation facility an array of magnetically operated sensors, reed switches, Hall devices, etc. are arranged to operate on a ternary system, as contrasted to a binary system, by providing each sensor with a selectively magnetized bias magnet, either a permanent magnet or an electromagnet, so that each sensor is responsive to the polarity as well as field strength of a corresponding permanent or electromagnetic operate magnet of an array of operate magnets movable into juxtaposition to the array of sensors. The sensors are connected either all in series to complete a controlled circuit or all in parallel to open a controlled circuit and each sensor is arranged to respond to magnetic fields of a bias and an operate magnet and is therefore in a first state unless both magnets are demagnetized or have polarities that neutralize each other in the region of the sensor. When remanent magnets, i.e. magnets having high retentivity, are employed as operate magnets a corresponding array of electromagnets is provided to selectively magnetize with selected polarity or demagnetize each magnet of the array of magnets to impress an address code on the operate magnet array. A similar array of electromagnets, when juxtaposed to the array of sensors selectively magnetizes the array of bias magnets to condition the array to respond to a particular address code.

United States Patent [191 Eggert [111 3,784,942 Jan. 8, 1 974 TERNARY ESCORT MEMORY SYSTEM [75] Inventor: Glenn J. Eggert, Milwaukee, Wis.

[73] Assignee: Rex 'Chainbelt Inc., Milwaukee, Wis.

[22] Filed: Nov. 17, 1972 [21] Appl. No.: 307,600

[52] US. Cl. .t 335/206, 335/207 [51] Int. Cl. H01h H0lh 36/00 [58] Field of Search 335/205-207, 153

[56] References Cited UNITED STATES PATENTS 3,506,939 4/1970 Hesser et al. 335/206 8/197] Suzuki 335/206 X Primary Examiner Roy N. Envall, Jr Att0rneyCharles 0. Marshall Jr. et al.

[57] ABSTRACT In an addressing system of a transportation facility an array of magnetically operated sensors, reed switches, Hall devices, etc. are arranged to operate on a ternary system, as contrasted to a binary system, by providing each sensor with a selectively magnetized bias magnet, either a permanent magnet or an electromagnet, so that each sensor is responsive to the polarity as well as field strength of a corresponding permanent or elec tromagnetic operate magnet of an array of operate magnets movable into juxtaposition to the array of sensors. The sensors are connected either all in series to complete a controlled circuit or all in parallel to open a controlled circuit and each sensor is arranged to respond to magnetic fields of a bias and an operate magnet and is therefore in a first state unless both magnets are demagnetized or have polarities that neutralize each other in the region of the sensor. When remanent magnets, i.e. magnets having high retentivity, are employed as operate magnets a corresponding array of electromagnets is provided to selectively mag netize with selected polarity or demagnetize each magnet of the array of magnets to impress an address code on the operate magnet array. A similar array of electromagnets, when juxtaposed to the array of sensors selectively magnetizes the array of bias magnets to condition the array to respond to a particular address code.

8 Claims, 11 Drawing Figures PATENTEDJAH 8 m4 7 8 W W NS N 1 TERNARY ESCORT MEMORY SYSTEM SUMMARY OF THE INVENTION This invention relates to an escort memory or addressing system for a conveyor system in which each car or carrier of the system carries information identifying the destination of the load in the car or carrier in pressed in binary form and must include not only the destination code but also information to operate the proper switches to select the route. With the increase in number of discharge stations and switches, it is desirable to provide a maximum of address information with a minimum of equipment as well as simplifying the equipment and its method of use.

According to the invention, each address is expressed as a multiplace number in a ternary (base 3) system instead of the usual binary (base 2) numbering system. Each article carrier of the conveyor system carries an address plate that includes a magnetizable permanent magnet remanent magnet for each place of the multiplace number. A reader cooperates with the address plate, to actuate a track switch or discharge operation. Each reader is mounted in the trackway just ahead of the associated switch or discharge station. The reader includes a magnetically actuated switch, such as a magnetic reed switch and a bias magnet for each place of the ternary number. The cooperation of the two magnets allows threestates of the address magnet to be identified, i.e. no magnetization, magnetized NS, and magnetized S-N. The magnetic state of the bias magnet determines which of the three states will actuate the cooperating switch. The switches may be connected in series to complete a circuit or in parallel to break a circuit when the proper code is read.

A preferred form of the invention is illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a conveyor system in which the improved address equipment may be used.

FIG. 2 is a schematic end elevation ofa car and truck showing a preferred location of the address member and reader.

FIG. 3 is a plan view showing the locations of the magnets in an address plate or reader.

FIG. 3a is a vertical section along the line 3a3a of FIG. 3.

FIG. 4 is a circuit diagram of the reader when ar- These specific figures and the accompanying description are intended to illustrate the invention and not to impose limitations on the claims.

DESCRIPTION OF A PREFERRED EMBODIMENT Escort memory systems are required in conveyor systems in which individual carriers are to be dispatched to given destinations and, in particular, in such systems in which the carrier may follow any of a number of routes in traveling between a loading station and a destination. A generally schematically layout of such a sys tem is illustrated in FIG ll. As indicated in this figure, cars may travel around a main loop 1, from which they may be diverted by switching means indicated by cross lines 2, onto any one of a plurality of minor loops 3, 4, 5, 6, or 7. The loop 4 is shown as being further divided into several sub-loops 8 and 9. In a luggage handling system of an airport, for example, the minor loops 6 and 7 might be arranged to serve ticket counters or check-in stations, while the loops 3 and 4 may serve gate loading areas and loop 5 may be a storage area for cars not required at the particular moment of time. In an actual installation there may be many more loading stations and many more discharge points as well as more interconnecting loops, so that the capacity of the address plate must be quite large.

Referring to FIG. 2, a typical carrier for the conveyor system may comprise a car 10 carried on wheels 11 that run on a track 12. As ordinarily arranged, the upstanding walls on each of the tracks 12 is continued on the out-side rails through each of the switch points and is cut away on the inside rails through the switch. The car is guided through a switch by probes or guides 13 that are individually lowerable to engage the outside of the upstanding track wall so as to either guide the car straight through a switch if a first one of the probes I3 is down or onto a diverging track if the other of the probes is lowered. The probes are interlocked so that only one can be down at a time and are further arranged with over-center springs in a toggle arrangement so that once a probe is lowered it must be forcibly pushed up to lower the other probe. The switching mean comprises a movable inclined cam that is raised to operative position in repsonse to signal from the cooperating reader to raise one or the other of the probes according to the desired travel of the car through the next switch. Any suitable electromechanical or electropneumatic means may be used to operate the cams in response to electrical signals received from a reader 15, positioned in the trackway. The reader 15 cooperates with or reads the information stored in an address plate 16, attached to the lower side of the car 10.

The address plate 16 is a flat member containing a plurality of magnetizable remanent or permanent magnets 17A, 17B, etc. approximately equally spaced along the longitudinal axis of the plate and each extending transversely to such axis. The term magnetizable remanent or permanent magnet denotes a bar of high retentivity magnetic material that may be demagnetized or magnetized by an appropriately energized electromagnet 18 (FIG. 3a) and which when so magnetized remains in such magnetized state until again either demagnetized or magnetized in reverse direction. Each of these magnets may be in any one of three distinct magnetic states, i.e., may be demagnetized, or may be magnetized with a North-South polarity or with a South- North polarity. The address plate also includes further permanent magnets S, which are always magnetized and which cooperate with switches in corresponding positions in the reader when the address plate is in proper position over the reader to be read.

The reader is physically similar to the address plate 16, shown in FIG. 3 with the exception that a magnetically actuated switch such as a reed switch is positioned at each of the magnet locations A through D and at the two end positions S. In addition, each of the switches at the positions A through D is provided with a bias magnet which determines its response to the operate magnets A through D of the address plate 16. The switches 20, as shown in FIG. 4, are all connected in series if it is desired to complete or close a circuit in response to the sensing or reading of a corresponding code or, alternatively, the switches may be all connected in parallel, as shown in FIG. 5, in the event it is desired to open a circuit in response to sensing a corresponding code.

In a preferred form, each of the switches is a magnetically actuated reed switch which, as shown in FIG. 6, comprises a casing 21, usually of glass, that hermetically encloses a set of contacts including a magnetic fixed contact 22, a fixed nonmagnetic contact 23, and a movable contact 24. In the absence of a magnetic field the movable contact 24 engages the fixed nonmagnetic contact 23. This is considered to be the normally closed position of the switch. Each of the switches is further provided with a bias magnet 25, with the exception of the switches in the position S at each end of the reader. Bias magnets are not required for the end switches S because the cooperating magnets in the address plate are always magnetized and only the magnetized state is read or sensed.

When the bias magnet 25, is demagnetized the cooperating reed switch is in its closed position, as indicated in FIG. 6. If the magnet is magnetized with either polarity, such as indicated in FIG. 7, the cooperating reed switch 20 is in its open position. The bias magnet enables the reed switch to distinguish one of the three possible magnetic states of the address magnet 17 from the other two states. First, if the bias magnet is demagnetized, the condition illustrated in FIG. 6, the switch is moved to its open position by an operate magnet 17, magnetized in either polarity. Thus in order for the switch to remain closed in the reading position the corresponding address plate of the magnet must be demagnetized.

If the bias magnet is magnetized, for example as shown in FIGS. 7, 8, and 9, the switch is open if the corresponding operate magnet 17 is absent or demagnetized. Also the switch is open if the operate magnet is magnetized with the same polarity as the bias magnet 25. In this condition, as illustrated in FIG. 8, the magnetic fields of the two magnets add through the switch so as to merely increase the magnetic force holding the movable contact 24 of the switch-in contact with the fixed magnetic contact 22. Thus the switch is open in two of the three magnetic states of the operate magnet 17. However if the operate magnet 17 is magnetized with the opposite polarity to the bias magnet, the condition shown in FIG. 9, the two magnets cancel each other with respect to flux flowing through the movable contact of the switch and as a result the switch moves to its closed position.

While reed switches have been indicated as a preferred form of magnetically operated switch, other types of magnetic devices may also be employed. For example, semiconductor devices employing the Hall effect are quite satisfactory. lf Hall effect devices are used a pair is required for each magnet, as shown in FIG. 10, because the devices are sensitive to the polarity of the magnetic flux whereas the reed switch is not.

This particular arrangement of bias magnets cooperating with magnetically operated reed switches or similar devices offers the advantage that all of the units may be constructed and wired precisely alike, i.e., the readers are all identical as far as mechanical and electrical construction is concerned. Each reader is conditioned to respond to a particular code by selective magnetization of its bias magnets. This magnetic conditioning operation is the same as impressing an address code on the address plate 16 as is done at each loading station of the conveyor system. The conditioning of the readers and the impressing of the address is done with an array of electromagnets, each being similar to the electromagnet 18 shown in FIG. 3a, with the electromagnets spaced along the length of the reader or address plate according to the positions of the magnets 17, FIG. 3. Any of the magnets may be magnetized by providing either direct current of the proper polarity or half wavc alternating current of the proper polarity to the coil of the electromagnet. The demagnetized state may be obtained by suppling the electromagnet 18 with an alternating current signal that decrease in magnitude with time. This has the effect of alternately reversing the magnetization with each reversal being less than the previous so as to leave the permanent magnet in a demagnetized position.

The advantages of the ternary system, as shown, over a straight binary system is readily apparent when one considers that a four channel system as shown with magnets A, B, C, and D provides 8] unique combinations in the ternary system whereas the same number of magnets in a binary system would yield only 16 combinations. The advantage in reduction of parts becomes much greater when the number of channels is increased. For example, with six channels a ternary system provides 729 combinations as compared to 64 for a binary system.

It is also possible to substitute electromagnets for the bias magnets 25 thus affording the possibility of changing the code to which the reader responds by switching the current flow in the various electromagnets that bias the reed switches.

The foregoing description is intended merely to illustrate the invention not to impose limitations on the claims.

I claim:

1. In a coded magnetically actuated switching system, in combination, an array of magnetically actuated sensors connected in an And circuit, each of said sensors having a first state in the absence of a magnetic field, a magnetizable bias magnet mounted in cooperative relation adjacent each sensor and effective when magnetized to hold the adjacent sensor in a second state, an array of magnetizable operate magnets selectively magnetized according to code that is movable into operative relation to the array of sensors, each sensor being in its first state when the magnetic state of the corresponding magnetizable operate magnet corresponds to the magnetic state of its bias magnet.

2. A system according to claim 1 in which each of the bias magnets is a magnetizable permanent magnet.

7. A system according to claim 6 in which the switches are connected in series and each closes in response to the absence of a magnetic field in the region of the switch.

8. A system according to claim 1 in which the magnetically actuated sensors are Hall effect devices operatively arranged in an And circuit. 

1. In a coded magnetically actuated switching system, in combination, an array of magnetically actuated sensors connected in an ''''And'''' circuit, each of said sensors having a first state in the absence of a magnetic field, a magnetizable bias magnet mounted in cooperative relation adjacent each sensor and effective when magnetized to hold the adjacent sensor in a second state, an array of magnetizable operate magnets selectively magnetized according to code that is movable into operative relation to the array of sensors, each sensor being in its first state when the magnetic state of the corresponding magnetizable operate magnet corresponds to the magnetic state of its bias magnet.
 2. A system according to claim 1 in which each of the bias magnets is a magnetizable permanent magnet.
 3. A system according to claim 1 in which each of the bias magnets is an electromagnet.
 4. A system according to claim 1 in which each of the operate magnets is a magnetizable permanent magnet.
 5. A system according to claim 1 including an array of electromagnets for selectively magnetizing the arrays of operate magnets and bias magnets.
 6. A system according to claim 1 in which the magnetically actuated sensors are reed switches.
 7. A system accordinG to claim 6 in which the switches are connected in series and each closes in response to the absence of a magnetic field in the region of the switch.
 8. A system according to claim 1 in which the magnetically actuated sensors are Hall effect devices operatively arranged in an And circuit. 